Polymer blends with improved impact resistance

ABSTRACT

Polymer blends, in particular polyphenylene ether-polyamide blends, are effectively compatibilized by incorporating under blending conditions certain oligomers, cooligomers, polymers and copolymers of narrow molecular weight distribution that are prepared under free radical polymerization conditions with glycidyl-functionalized nitroxyl initiators. The oligomers, cooligomers, polymers and copolymers contain at least one oxyamine group and at least one glycidyl-containing initiator group. The polymer blends have excellent mechanical properties.

[0001] The present invention relates to polymer blends with improvedmechanical properties, in particular polyphenylene ether-polyamide resinblends.

[0002] Polyphenylene ethers, also called polyphenylene oxides, andabbreviated as PPE or PPO, are a widely used class of thermoplasticengineering resins characterized by excellent hydrolytic stability,dimensional stability, toughness, heat resistance and dielectricproperties. However, they are deficient in certain other properties suchas workability and solvent resistance. Therefore, there is a continuingsearch for means for modifying polyphenylene ethers to improve theirdeficiencies.

[0003] In order to overcome these problems polyphenylene ethers areblended with other resins such as polyesters, polyamides or olefinpolymers. Blends of polyphenylene ethers with polyamides such as nylon6,6 are of particular interest. Such blends are inherently incompatibleand therefore “compatibilizing” agents are necessary to achieve thedesired properties. Without compatibilizing agents molded articles madefrom these blends have inferior mechanical properties, such as lowimpact strength. There has been an extensive amount of work aimed atimproving the compatibility of blends of polyphenylene ether andpolyamide resins.

[0004] Attempts have been made towards grafting polyphenylene etherdirectly to the polyamide. For example U.S. Pat. No. 4,315,086 describesthe use of a polyfunctional compound selected from the group consistingof liquid diene polymers, epoxy compounds and compounds having bothunsaturation and a reactive group such as a carboxylic acid, anhydride,ester, etc. for this purpose. The epoxy compounds are well known epoxyresins and the like. U.S. Pat. Nos. 4,873,286 and 5,000,897 disclose theuse of aliphatic polycarboxylic acids or derivatives for grafting orpartially grafting polyphenylene ether with polyamide. U.S. Pat. No.4,824,915 teaches the use of a multi-functional compound containing forexample, an acid chloride group and an anhydride group for this purpose.

[0005] Other workers have focused on the formation of copolymers ofpolyphenylene ether and polyamide to effect their compatibility. U.S.Pat. No. 4,600,741 discloses the use of polyphenylene etherfunctionalized with carboxylic acid and derivatives for this purpose.U.S. Pat. No. 4,732,937 teaches the use of epoxy functionalizedpolyphenylene ether in order to form a copolymer with a polyester orpolyamide.

[0006] U.S. Pat. Nos. 5,041,504, 5,096,979 and 5,100,961 and EP 347,539disclose the use of epoxytriazine-capped polyphenylene ether to formcopolymers with polyamides for the purposes of forming compatible blendsof the two polymers.

[0007] U.S. Pat. No. 5,231,146 teaches blends of polyphenylene ether andblock polyetheramides with good mechanical properties with theincorporation of a polyepoxide. Preferred polyepoxides are triglycidylfunctionalized triazine derivatives. Also mentioned are copolymers ofglycidyl acrylate and glycidyl methacrylate with polyacrylates,polyacrylonitrile and polystyrene. DE3837647 teaches compatibilizationof polyphenylene ether-polyamide blends with the use of glycidyltriazine derivatives.

[0008] U.S. Pat. No. 4,659,763 discloses the use of quinone compounds ascompatibilizing agents for blends of polyphenylene ether and polyamide.

[0009] Chiang and Chang, in the Journal of Applied Polymer Science,61(13), 1996,2411-2421, discusses compatibilizing blends ofpolyphenylene oxide and polyamide-6 with styrene-glycidyl methacrylatecopolymers. The same workers, in the Journal of Polymer Science: Part B:Polymer Physics, 36(11), 1998, 1805-1819, disclose that atetrafunctional epoxy monomer,N,N,N′N′-tetraglycidyl-4,4′-diaminodiphenyl methane, is an efficientcompatibilizer for polyphenylene ether-polyamide-6 blends.

[0010] U.S. Pat. No. 5,141,984 discloses compatibilizing blends ofpolyamide resins with polyphenylene ether or polycarbonate resins with amixture of an epoxy group-containing olefin copolymer and a vinylpolymer or copolymer.

[0011] Dedecker and Groeninckx, in Pure Appl. Chem. 70(6), 1998,1289-1293, teaches compatibilization of polystyrene or polyphenyleneoxide with polyamide-6 with the use of a maleic anhydride-styrenecopolymer. The anhydride groups of the copolymer react with the aminoend groups of polyamide-6 and the copolymer is miscible with polystyreneor polyphenylene oxide, giving rise to the formation of a graftcopolymer at the interface.

[0012] Kim and Jo, in Polymer Engineering and Science, 35(8), 1995,648-657, teach that a partially hydrolyzed styrene/t-butyl acrylatediblock copolymer performs as a compatibilizer for polyphenyleneether-polyamide-6 blends. Presumably, the amine end groups of thepolyamide react with the carboxyl groups of the partially hydrolyzeddiblock copolymer.

[0013] DE 3644208 discloses compatibilizing blends of polyphenyleneether-polyamide resins with a polyphenylene ether containing epoxygroups and a styrene resin. JP2245063 teaches polyphenyleneether-polyamide blends which exhibits a good balance of overallproperties by incorporating a copolymer obtained from styrene, anepoxy-containing monomer and another monomer. DE3924237 disclosescompatibilizing thermoplastic resins containing polar residues withpolyphenylene ether by employing styrene resin with epoxy residues andstyrene without epoxy groups.

[0014] EP 747440 discloses the compatibilization of polyphenyleneether-polyamide blends while maintaining good impact strength with aknown compatibilizing compound and in the presence of a known impactmodifying agent. Among the compatibilizers are epoxy compounds, andamong the impact modifying agents are AB block copolymers such asstyrene-butadiene or styrene-isoprene.

[0015] Kobatake, et al., in Macromolecules, 31(11), 1998, 3735-3739,discloses an epoxy-functionalized nitroxyl compound. The epoxy group isused as a terminator for polybutadiene prepared by anionicpolymerization. The nitroxy-functionalized polybutadiene is used as amacroinitiator in the formation of styrene-butadiene block copolymers.

[0016] U.S. Pat. No. 4,581,429, to Solomon et al., issued Apr. 8, 1986,discloses a free radical polymerization process which controls thegrowth of polymer chains to produce short chain or oligomerichomopolymers and copolymers, including block and graft copolymers. Theprocess employs an initiator having the formula (in part) R′R″N—O—X,where X is a free radical species capable of polymerizing unsaturatedmonomers. Specifically mentioned R′R″N—O radical groups are derivedfrom tetraethylisoindoline, tetrapropylisoindoline,tetramethylpiperidine, tetramethylpyrrolidine or di-t-butylamine.

[0017] U.S. Pat. No. 5,721,320 and WO 97/36944 disclose the preparationof rubber-reinforced polymers by polymerizing a vinyl aromatic monomerin the presence of a diene rubber having at least one stable freeradical group, under polymerization conditions such that a vinylaromatic-diene block and/or graft copolymer rubber is formed. Examplesof stable free radical groups given are nitroxyl groups. U.S. Pat. No.5,891,971 teaches the preparation of polymers with narrow polydispersityusing alkoxyamine initiators. U.S. Pat. Nos. 5,627,248 and 5,677,388disclose the free-radical polymerization of vinyl aromatic monomersusing a difunctional nitroxyl initiator. Hawker in J. Am. Chem. Soc.,116, 1994, 11185-11186, discloses the preparation of low polydispersitypolystyrene with a hindered alkoxyamine compound.

[0018] Benoit, et al., in J. Am. Chem. Soc., 121(16), 1999, 3904-3920,discloses the polymerization of styrene with molecular weight andpolydispersity control using a variety of alkoxyamine initiators.

[0019] Surprisingly, it has been found that certain oligomers, polymers,cooligomers or copolymers (block or random) of narrow molecular weightdistribution, and whose polymerization is initiated withglycidyl-functionalized nitroxyl derivatives, are especially effectiveat forming copolymers with polyamides under blending conditions; thesecopolymers in turn are especially effective as compatibilizers for thepolyphenylene ether-polyamide blends. The improved compatibility ofblends of polyphenylene ethers and polyamides comprising these novelcopolymers is exhibited in the form of excellent mechanical propertiessuch as impact strength.

[0020] The (co)oligomers and (co)polymers of narrow molecular weightdistribution, and whose polymerization is initiated withglycidyl-functionalized nitroxyl derivatives contain at least oneglycidyl initiator group and at least one oxyamine group as discussedinfra. For the purposes of this invention they may be generally referredto as compatibilizers or compatibilizing agents.

[0021] Presumably, the epoxy functional groups of the resultant(co)oligomers and (co)polymers react with the amine and/or thecarboxylic acid end groups of the polyamide under blending conditions toform the novel polyamide-copolymer-compatibilizers. The (co)oligomer or(co)polymer itself is one that is compatible with polyphenylene ether.In this way highly compatible polyphenylene ether-polyamide mixtures areobtained when blended in the presence of the epoxy-containing(co)oligomers or (co)polymers.

[0022] For example, if the oligomer or polymer containing the glycidyland oxyamine groups is a polystyrene, a composition comprisingpolyphenylene ether, polyamide, and the glycidyl-functionalizedpolystyrene, and subjected to normal blending conditions will form apolystyrene-polyamide copolymer. The polystyrene is miscible with thepolyphenylene ether, and hence under such conditions a highly compatibleblend of polyphenylene ether-polyamide will result. It is not necessarythat all of the polyamide form copolymer; that is to say the highlycompatible polyphenylene ether-polyamide blends of the instant inventionmay contain unreacted polyamide. The resultant highly compatible blendexhibits excellent impact strength.

[0023] The oligomers, polymers, cooligomers or copolymers containingglycidyl and oxyamine groups of the instant invention, prepared byfree-radical polymerization of at least one ethylenically unsaturatedmonomer or oligomer in the presence of a glycidyl-functionalizednitroxyl initiator are also useful for compatibilizing other knownpolymer blends. Polyesters, containing terminal carboxylic acid groups,are also known to react with epoxides. Therefore, where appropriate,polyesters may be substituted for polyamides in the blends describedabove.

[0024] Further, the (co)oligomers or (co)polymers containing glycidyland oxyamine groups of the instant invention are useful towardscompatibilizing blends of polystyrene with polyesters as well as blendsof polystyrene with polyamides.

[0025] An object of this invention therefore, is to provide a novelcomposition comprising

[0026] i.) a polymer selected from the group consisting of polyphenyleneether and polystyrene,

[0027] ii.) at least one other polymer containing amine or carboxylicacid end groups, and

[0028] iii.) an oligomer, polymer, cooligomer or copolymer prepared byfree-radical polymerization of at least one ethylenically unsaturatedmonomer or oligomer in the presence of a glycidyl-functionalizednitroxyl initiator.

[0029] Another object of this invention is to provide a novel method forpreparing highly compatible polymer mixtures comprising blending underintimate blending conditions

[0030] i.) a polymer selected from the group consisting of polyphenyleneether and polystyrene,

[0031] ii.) at least one other polymer containing amine or carboxylicacid end groups,

[0032] iii.) an oligomer, polymer, cooligomer or copolymer prepared byfree-radical polymerization of at least one ethylenically unsaturatedmonomer or oligomer in the presence of a glycidyl-functionalizednitroxyl initiator, and

[0033] iv.) optional further additives.

[0034] Preferably, the polymer of component i.) is a polyphenylene etherand the polymer of component ii.) is a polyamide.

[0035] The glycidyl-functionalized nitroxyl initiators employed in thepreparation of the (co)oligomers or (co)polymers of narrow molecularweight distribution of the instant invention are of the formulae

[0036] wherein

[0037] R are independently hydrogen, halogen, NO₂, cyano, —CONR₅R₆,—(R₉)COOR₄, —C(O)—R₇, —OR₈, —SR₈, —NHR₈, —N(R₈)₂, carbamoyl,di(C₁-C₁₈alkyl)carbamoyl, —C(═NR₅)(NHR₆) or R has the same definition asR₁;

[0038] R₁ are independently unsubstituted C₁-C₁₈alkyl, C₂-C₁₈alkenyl,C₂-C₁₈alkynyl, C₇-C₉phenylalkyl, C₃-C₁₂cycloalkyl orC₂-C₁₂heterocycloalkyl; or C₁-C₁₈alkyl, C₂₋C₈alkenyl, C₂-C₁₈alkynyl,C₇-C₉phenylalkyl, C₃-C₁₂cycloalkyl or C₂-C₁₂heterocycloalkyl, which aresubstituted by NO₂, halogen, amino, hydroxy, cyano, carboxy,C₁-C₄alkoxy, C₁-C₄alkylthio, C₁-C₄alkylamino or di(C₁-C₄alkyl)amino; orphenyl, naphthyl, which are unsubstituted or substituted by C₁-C₄alkyl,C₁-C₄alkoxy, C₁-C₄alkylthio, halogen, cyano, hydroxy, carboxy,C₁-C₄alkylamino or di(C₁-C₄alkyl)amino;

[0039] R₄ is hydrogen, C₁-C₁₈alkyl, phenyl, an alkali metal cation or atetraalkylammonium cation;

[0040] R₅ and R₆ are hydrogen, C₁-C₁₈alkyl, C₂-C₁₈alkyl which issubstituted by at least one hydroxy group or, taken together, form aC₂-C₁₂alkylene bridge or a C₂-C₁₂-alkylene bridge interrupted by atleast one O or/and NR₈ atom;

[0041] R₇ is hydrogen, C₁-C₁₈alkyl or phenyl;

[0042] R₈ is hydrogen, C₁-C₁₈alkyl or C₂-C₁₈alkyl which is substitutedby at least one hydroxy group;

[0043] R₉ is C₁-C₁₂alkylene or a direct bond; or all R₁ form togetherthe residue of a polycyclic cycloaliphatic ring system or a polycyclicheterocycloaliphatic ring system with at least one di- or trivalentnitrogen atom;

[0044] R₂ are independently of each other phenyl or C₁-C₆alkyl or twotogether with the linking carbon atom form a C₅-C₆cycloalkyl group;

[0045] A is a divalent group which forms a carbocyclic or heterocyclic5-, 6- or 7-membered ring which may be further substituted; and

[0046] R₃ is a radical of formula (II)

[0047] X is phenylene, naphthylene or biphenylene, which areunsubstituted or substituted by NO₂, halogen, amino, hydroxy, cyano,carboxy, C₁-C₄alkoxy, C₁-C₄alkylthio, C₁-C₄alkylamino ordi(C₁-C₄alkyl)amino;

[0048] R₁₂ are independently of each other H or CH₃;

[0049] D is a group

[0050] m is a number from 1 to 4.

[0051] Halogen is fluoro, chloro, bromo or iodo.

[0052] The alkyl radicals in the various substituents may be linear orbranched. Examples of alkyl containing 1 to 18 carbon atoms are methyl,ethyl, propyl, isopropyl, butyl, 2-butyl, isobutyl, t-butyl, pentyl,2-pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, t-octyl, nonyl, decyl,undecyl, dodecyl, tridecyl, tetradecyl, hexadecyl and octadecyl.

[0053] The alkenyl radicals in the various substituents may be linear orbranched. Examples of C₂-C₁₈alkenyl are vinyl, allyl, 2-methylallyl,butenyl, hexenyl, undecenyl and octadecenyl. Preferred alkenyls arethose, wherein the carbon atom in the 1-position is saturated and wherethe double bond is not activated by substituents like O, C═O, and thelike.

[0054] Examples of C₂-C₁₈alkynyl are ethynyl, 2-butynyl, 3-hexynyl,5-undecynyl, 6-octadecynyl. The alkynyl radicals may be linear orbranched.

[0055] C₇-C₉phenylalkyl is for example benzyl, phenylpropyl,α,α-dimethylbenzyl or α-methyl-benzyl.

[0056] C₃-C₁₂cycloalkyl which is unsubstituted or substituted by 1, 2 or3 C₁-C₄alkyl is typically cyclopropyl, cyclopentyl, methylcyclopentyl,dimethylcyclopentyl, cyclohexyl, methylcyclohexyl.

[0057] Alkyl substituted by-OH is typically 2-hydroxyethyl,2-hydroxypropyl or 2-hydroxybutyl. C₁-C₁₈Alkyl substituted byC₁-C₈alkoxy, preferably by C₁-C₄alkoxy, in particular by methoxy orethoxy, is typically 2-methoxyethyl, 2-ethoxyethyl, 3-methoxypropyl,3ethoxypropyl, 3-butoxypropyl, 3-octoxypropyl and 4-methoxybutyl.

[0058] C₁-C₁₈Alkyl substituted by di(C₁-C₄alkyl)amino is preferably e.g.dimethylamino, diethylamino, 2-dimethylaminoethyl, 2-diethylaminoethyl,3-dimethylaminopropyl, 3-diethylaminopropyl, 3-dibutylaminopropyl and4-diethylaminobutyl.

[0059] C₁-C₁₈Alkyl substituted by C₁-C₄alkylamino is preferably e.g.methylamino, ethylamino, 2-methylaminoethyl, 2-ethylaminoethyl,3-methylaminopropyl, 3-ethylaminopropyl, 3-butylamino-propyl and4-ethylaminobutyl.

[0060] C₁-C₈Alkoxy and, preferably C₁-C₄alkoxy, are typically methoxy,ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, pentoxy, isopentoxy,hexoxy, heptoxy or octoxy.

[0061] C₁-C₄Alkylthio is typically thiomethyl, thioethyl, thiopropyl,thioisopropyl, thiobutyl and thioisobutyl.

[0062] C₂-C₁₂heterocycloalkyl is typically oxirane, 1,4-dioxane,tetrahydrofuran, γ-butyrolactone, ε-caprolactam, oxirane, aziridine,diaziridine, pyrrole, pyrrolidine, thiophen, furan, pyrazole, imidazole,oxazole, oxazolidine, thiazole, pyran, thiopyran, piperidine ormorpholine.

[0063] Examples of C₂-C₁₂alkylene bridges, preferably of C₂-C₆alkylenebridges, are ethylene, propylene, butylene, pentylene, hexylene.

[0064] C₂-C₁₂alkylene bridges interrupted by at least one N or O atomare, for example, —CH₂—O—CH₂—CH₂, —CH₂—O—CH₂—CH₂—CH₂,—CH₂—O—CH₂—CH₂—CH₂—CH₂—, —CH₂—O—CH₂—CH₂—O—CH2—, —CH₂—NH—CH₂—CH₂,—CH₂—NH—CH₂—CH₂—CH₂, —CH₂—NH—CH₂—CH₂—CH₂—CH₂—, —CH₂—NH—CH₂—CH₂—NH—CH2-or —CH₂—NH—CH₂—CH₂—O—CH2- .

[0065] Phenyl substituted by 1, 2 or 3 C₁-C₄alkyl or C₁-C₄alkoxy istypically methylphenyl, dimethylphenyl, trimethylphenyl, t-butylphenyl,di-t-butylphenyl, 3,5-di-t-butyl4-methylphenyl, methoxyphenyl,ethoxyphenyl and butoxyphenyl.

[0066] Examples of polycyclic cycloaliphatic ring systems areadamantane, cubane, twistane, norbornane, bicyclo[2.2.2]octane orbicyclo[3.2.1]octane.

[0067] An example of a polycyclic heterocycloaliphatic ring system ishexamethylentetramine (urotropine).

[0068] Examples for a divalent group A required to form a cyclic 5-, 6-or 7-membered ring are: C₂-C₄alkylene, C₂-C₄alkenylene or 1,2 phenylenewhich groups may be unsubstituted or substituted by NO₂, halogen, amino,hydroxy, cyano, C₁-C₁₈ alkylcarboxy, C₁-C₁₈alkoxycarbonyl,C₁-C₁₈alkylcarbonyl, C₁-C₁₈alkoxy, benzyloxy, C₁-C₁₈alkanoyloxy,benzoyloxy, C₁-C₁₈alkylthio, C₁-C₁₈alkylamino, di(C₁-C₁₈alkyl)amino orphenyl.

[0069] When A has the meaning of C₂-C₄alkylene or C₂-C₄alkenylene, thesegroups may also be interrupted by an O or N atom.

[0070] C₂-C₄alkylene bridges interrupted by at least one N or O atomare, for example, —CH₂—O—CH₂—CH₂, —CH₂—O—CH₂—, —O—CH₂—CH₂—,—O—CH₂—O—CH2—, —CH₂—NH—CH₂—, —CH₂—, —CH₂—NH—CH₂—CH₂—, —NH—CH₂—CH₂—,—NH—CH₂—NH—CH2—, —O—CH₂— or —CH₂—O—C(O)—.

[0071] The C-atom to which the substituents R₁ are bound is preferably asecondary or tertiary C-atom more preferably it is a tertiary C-atom.

[0072] Preferred is a compound of formula (Ia) or (Ib),

[0073] wherein

[0074] Rare independently NO₂, cyano, —(R₉)COOR₄, —CONR₅R₆, —C(O)—R₇,—OR₈, carbamoyl, di(C₁-C₁₈alkyl)carbamoyl, —C(═NR₅)(NH₆) or R has thesame definition as R₁;

[0075] R₁ are independently unsubstituted C₁-C₈alkyl or C₅-C₇cycloalkyl;or phenyl, which is unsubstituted or substituted by C₁-C₄alkyl,C₁-C₄alkoxy, cyano, hydroxy, carboxy, C₁-C₄alkylamino ordi(C₁-C₄alkyl)amino;

[0076] R₄ is C₁-C₈alkyl, phenyl, an alkali metal cation or atetraalkylammonium cation;

[0077] R₅ and R₆ are hydrogen, C₁-C₈alkyl, C₂-C₈alkyl which issubstituted by at least one hydroxy group or, taken together, form aC₂-C₆alkylene bridge;

[0078] R₇ is, C₁-C₈alkyl or phenyl;

[0079] R₈ is C₁-C₈alkyl or C₂-C₈alkyl which is substituted by at leastone hydroxy group;

[0080] R₉ is C₁-C₄alkylene or a direct bond;

[0081] R₂ are independently C₁-C₆alkyl;

[0082] A is a divalent group which forms a carbocyclic or heterocyclic5-, 6- or 7-membered ring which may be further substituted; and

[0083] R₃ is a radical of formula (II)

[0084] X is phenylene, naphthylene or biphenylene, which areunsubstituted or substituted by NO₂, halogen, amino or hydroxy;

[0085] R₁₂ are independently of each other H or CH₃;

[0086] D is a group

[0087] m is a number from 1 to 4.

[0088] More preferred is a compound of formula (Ia) or (Ib),

[0089] wherein the group

[0090] is

[0091] R₂ are independently C₁-C₆alkyl;

[0092] A is a divalent group which forms a carbocyclic or heterocyclic5-, 6- or 7-membered ring which may be further substituted; and

[0093] R₃ is a radical of formula (II)

[0094] X is phenylene, naphthylene or biphenylene;

[0095] one R₁₂ is H and the other R₁₂ is CH₃;

[0096] D is a group

[0097] m is a number from 1 to 2.

[0098] Particularly preferred is a compound of formula (Ib), wherein

[0099] R₂ are independently CH₃ or C₂H₅;

[0100] A is a divalent group which forms a carbocyclic or heterocyclic5- or 6-membered ring which may be further substituted; and

[0101] R₃ is a radical of formula (II)

[0102] X is phenylene, naphthylene or biphenylene;

[0103] one R₁₂ is H and the other R₁₂ is CH₃;

[0104] D is a group

[0105] ; and

[0106] m is a number from 1 to 2.

[0107] Most preferred is a compound of formula (III)

[0108] R₃ has the meaning as defined above;

[0109] Y is H, OR₁₀, NR₁₀R₁₁, —O—C(O)—R₁₀ or NR₁₁—C(O)—R₁₀;

[0110] R₁₀ and R₁₁ independently are hydrogen, phenyl, C₁-C₁₈alkyl,C₂-C₁₈alkenyl, C₂-C₁₈alkynyl or C₂-C₁₈alkyl which is substituted by atleast one hydroxy group or, if Y is NR₁₀R₁₁, taken together, form aC₂-C₁₂alkylene bridge or a C₂-C₁₂alkylene bridge interrupted by at leastone O atom.

[0111] Among the most preferred compounds of formula III, those that areof particular use are where

[0112] Y is H, OR₁₀, NR₁₀R₁₁, —O—C(O)—R₁₀ or NR₁₁—C(O)—R₁₀; and

[0113] R₁₀ and R₁₁ are independently hydrogen or C₁-C₆alkyl.

[0114] The glycidyl-nitroxyl initiators of the present invention may beprepared in different ways according to known methods. These methods arefor example described in Macromol. Rapid Commun. 17, 149, 1996, MacromolSymp. 111, 47, (1996), Polym. Degr. Stab. 55, 323 (1997), Synlett 1996,330, and U.S. Pat. Nos. 5,498,679 and 4,921,962.

[0115] The method of reacting the nitroxyl with the correspondingethylene glycidylether in the presence of t-butyl hydroperoxide asdescribed in U.S. Pat. No. 4,921,962 is a preferred method. As describedin Tetrahedron Lett. 37, 4919, 1996, the reaction may also be carriedout photochemically in the presence of di-t-butyl peroxide.

[0116] The starting phenylglycidylethers are known and eithercommercially available or may be prepared according to EP 226543.

[0117] The oligomers, polymers, cooligomers or copolymers (block orrandom) of narrow molecular weight distribution and which are employedas compatibilizing agents for the polymer blends of the instantinvention are prepared by free radical polymerization of at least oneethylenically unsaturated monomer/oligomer, which comprises(co)polymerizing the monomer or monomers/oligomers in the presence of aninitiator compound of formula (Ia) or (Ib) under reaction conditionscapable of effecting scission of the O—R₃ (O—C) bond to form two freeradicals, the radical R₃ being capable of initiating polymerization.

[0118] Preferably the process is carried out in such a way that thescission of the O—C bond is effected by, heating ultrasonic treatment orexposure to electromagnetic radiation, ranging from γ to microwaves.

[0119] More preferred the scission of the O—C bond is effected byheating and takes place at a temperature of between 50° C. and 180° C.Preferred initiators are mentioned above.

[0120] The process may be carried out in the presence of an organicsolvent or in the presence of water or in mixtures of organic solventsand water. Additional co-solvents or surfactants, such as glycols orammonium salts of fatty acids, may be present. Other suitableco-solvents are described hereinafter.

[0121] Preferred processes use as little solvents as possible. In thereaction mixture it is preferred to use more than 30% by weight ofmonomer and initiator, particularly preferably more than 50% and mostpreferably more than 80%.

[0122] If organic solvents are used, suitable solvents or mixtures ofsolvents are typically pure alkanes (hexane, heptane, octane,isooctane), hydrocarbons (benzene, toluene, xylene), halogenatedhydrocarbons (chlorobenzene), alkanols (methanol, ethanol, ethyleneglycol, ethylene glycol monomethyl ether), esters (ethyl acetate,propyl, butyl or hexyl acetate) and ethers (diethyl ether, dibutylether, ethylene glycol dimethyl ether), or mixtures thereof.

[0123] The aqueous polymerization reactions can be supplemented with awater-miscible or hydrophilic co-solvent to help ensure that thereaction mixture remains a homogeneous single phase throughout themonomer conversion. Any water-soluble or water-miscible co-solvent maybe used, as long as the aqueous solvent medium is effective in providinga solvent system which prevents precipitation or phase separation of thereactants or polymer products until after all polymerization reactionshave been completed. Exemplary co-solvents useful in the presentinvention may be selected from the group consisting of aliphaticalcohols, glycols, ethers, glycol ethers, pyrrolidines, N-alkylpyrrolidinones, N-alkyl pyrrolidones, polyethylene glycols,polypropylene glycols, amides, carboxylic acids and salts thereof,esters, organosulfides, sulfoxides, sulfones, alcohol derivatives,hydroxyether derivatives such as butyl carbitol or cellosolve, aminoalcohols, ketones, and the like, as well as derivatives thereof andmixtures thereof. Specific examples include methanol, ethanol, propanol,dioxane, ethylene glycol, propylene glycol, diethylene glycol, glycerol,dipropylene glycol, tetrahydrofuran, and other water-soluble orwater-miscible materials, and mixtures thereof. When mixtures of waterand water-soluble or water-miscible organic liquids are selected as theaqueous reaction media, the water to co-solvent weight ratio istypically in the range of about 100:0 to about 10:90.

[0124] When monomer mixtures or monomer/oligomer mixtures are used, thecalculation of mol % is based on an average molecular weight of themixture.

[0125] Hydrophilic monomers, polymers and copolymers of the presentinvention can be separated from one another or from the polymerizationreaction mixture by, for example, changing the pH of the reaction mediaand by other well known conventional separation techniques.

[0126] The polymerization temperature may range from about 50° C. toabout 180° C., preferably from about 80° C. to about 150° C. Attemperatures above about 180° C., the controlled conversion of themonomer into polymer decreases, and uncertain and undesirableby-products like thermally initiated polymer are formed or destructionof the polymerization regulator may occur. Frequently, these by-productsdiscolor the polymer mixture and a purification step may be required toremove them, or they may be intractable.

[0127] Therefore the surprisingly high reactivity of the presentinitiators which are already active at relatively low temperatures leadsto short reaction times. The resulting polymers are usually colorlessand they can be used in most cases without any further purificationstep. This is an important advantage when industrial scale-up isconsidered.

[0128] After the polymerizing step is complete, the formed (co)polymerobtained is isolated. The isolating step of the present process isconducted by known procedures, e.g. by distilling off the unreactedmonomer or by precipitation in a suitable non-solvent, filtering theprecipitated polymer followed by washing and drying the polymer.

[0129] Block copolymers may be prepared and involves at least twostages, which comprises forming a polymer with alkoxyamine end groups ofthe general structure of formula (IVa) or (IVb)

[0130] wherein

[0131] R₁, R₂ and A are as defined above including the preferences, thepolymer containing the initiator group —R₃ and having the oxyamine groupessentially attached as terminal group, and adding a further monomerfollowed by heating to form a block copolymer by radical initiatedpolymerization.

[0132] The polymer of formula (IVa) or (IVb) may be isolated prior tothe next reaction step or it may be used without isolation, and thesecond monomer is added to the reaction mixture of the first step.

[0133] Furthermore, block copolymers of this invention may consist ofblocks which alternate between polar monomers and non-polar monomers.

[0134] The (co)polymers of the present invention may have a numberaverage molecular weight from 1,000 to 400,000 g/mol, preferably from2,000 to 250,000 g/mol and, more preferably, from 2,000 to 200,000g/mol. When produced in bulk, the number average molecular weight may beup to 500,000 (with the same minimum weights as mentioned above). Thenumber average molecular weight may be determined by-size exclusionchromatography (SEC), gel permeation chromatography (GPC), matrixassisted laser desorption/ionization mass spectrometry (MALDI-MS) or, ifthe initiator carries a group which can be easily distinguished from themonomer(s), by NMR spectroscopy or other conventional methods.

[0135] Because the present polymerization is a “living” polymerization,it can be started and stopped practically at will. Furthermore, thepolymer product retains the functional alkoxyamine group allowing acontinuation of the polymerization in a living matter. Thus, once thefirst monomer is consumed in the initial polymerizing step a secondmonomer can then be added to form a second block on the growing polymerchain in a second polymerization step. Therefore it is possible to carryout additional polymerizations with the same or different monomer(s) toprepare multi-block copolymers.

[0136] Furthermore, since this is a radical polymerization, blocks canbe prepared in essentially any order. One is not necessarily restrictedto preparing block copolymers where the sequential polymerizing stepsmust flow from the least stabilized polymer intermediate to the moststabilized polymer intermediate, such as is the case in ionicpolymerization. Thus it is possible to prepare a multi-block copolymerin which a polyacrylonitrile or a poly(meth)acrylate block is preparedfirst, then a styrene or butadiene block is attached thereto, and so on.

[0137] Furthermore, there is no linking group required for joining thedifferent blocks of the present block copolymer. One can simply addsuccessive monomers to form successive blocks.

[0138] The oligomers, polymers, cooligomers or copolymers of the presentinvention contain at least one initiator group —R₃ and at least oneoxyamine group of formula

[0139] wherein

[0140] A, R₁ and R₂ are as defined above.

[0141] Typically the amount of the initiator compound of formula (Ia) or(Ib) is in the range of 0.01 mol- % to 30 mol- % based on the monomer,oligomer or monomer/oligomer mixture used. If monomer mixtures are usedthe average molecular weight is taken for calculating mol- %.

[0142] The initiator compound of formula (Ia) or (Ib) is preferablypresent in an amount of 0.01 mol- % to 10 mol- %, more preferably in anamount of 0.05 mol- % to 5 mol- %, based on the monomer, oligomer ormonomer/oligomer mixture used.

[0143] The monomers suitable for use in the present invention may bewater-soluble or water-insoluble. Water soluble monomers containtypically a salt of a carboxylic acid group. Water insoluble monomersare typically free of acid and phenolic groups. Typical metal atoms areNa, K or Li.

[0144] Typical monoethylenically unsaturated monomers free of carboxylicacid and phenolic groups which are suitable for this invention includethe alkyl esters of acrylic or methacrylic acids such as methylacrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethylmethacrylate, butyl methacrylate and isobutyl methacrylate; thehydroxyalkyl esters of acrylic or, methacrylic acids, such ashydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethylmethacrylate, and hydroxypropyl methacrylate; acrylamide,methacrylamide, N-tertiary butylacrylamide, N-methylacrylamide,N,N-dimethylacrylamide; acrylonitrile, methacrylonitrile, allyl alcohol,dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate,phosphoethyl methacrylate, N-vinylpyrrolidone, N-vinylformamide,N-vinylimidazole, vinyl acetate, conjugated dienes such as butadiene orisoprene, styrene, styrenesulfonic acid salts, vinylsulfonic acid saltsand 2-acrylamido-2-methylpropane-sulfonic acid salts and acryloylchloride.

[0145] Preferred ethylenically unsaturated monomers or oligomers areselected from the group consisting of styrene, substituted styrene,conjugated dienes, acrolein, vinyl acetate, (alkyl)acrylicacidanhydrides, (alkyl)acrylic acid salts, (alkyl)acrylic esters and(alkyl)acrylamides.

[0146] Particularly preferred ethylenically unsaturated monomers arestyrene, α-methylstyrene, p-methylstyrene, isoprene and butadiene.

[0147] In a most preferred composition the ethylenically unsaturatedmonomer is styrene.

[0148] Preferred acrylates are methylacrylate, ethylacrylate,butylacrylate, isobutylacrylate, t-butylacrylate, hydroxyethylacrylate,hydroxypropylacrylate, dimethylaminoethylacrylate, glycidylacrylates,methyl(meth)acrylate, ethyl(meth)acrylate, butyl(meth)acrylate,hydroxyethyl(meth)acrylate, hydroxypropyl(meth)acrylate,dimethylaminoethyl(meth)acrylate, glycidyl(meth)acrylates,acrylonitrile, acrylamide or methacrylamide.

[0149] Examples for C₈-C₁₆ ethylenically unsaturated phenolics, whichmay also be used as comonomers include 4-hydroxystyrene,4-hydroxy-α-methylstyrene, and 2,6di-tert-butyl-4-vinylphenol.

[0150] Another class of carboxylic acid monomers suitable for use ascomonomers in this invention are the alkali metal and ammonium salts ofC₄-C₆-ethylenically unsaturated dicarboxylic acids. Suitable examplesinclude maleic acid, maleic anhydride, itaconic acid, mesaconic acid,fumaric acid and citraconic acid. Maleic anhydride (and itaconic acidare) is the preferred monoethylenically unsaturated dicarboxylic acidmonomer(s).

[0151] The acid monomers suitable for use in this invention are in theform of the alkali metal salts or ammonium salts of the acid.

[0152] The polyphenylene ethers and polyamides of the present inventionare as described in U.S. Pat. No. 5,100,961, the relevant parts of whichare incorporated herein by reference.

[0153] The polyphenylene ethers comprise a plurality of structural unitshaving the formula

[0154] and in each of said units independently, each Q₁ is independentlyhalogen, primary or secondary alkyl of 1 to 7 carbon atoms, phenyl,haloalkyl, aminoalkyl, hydrocarbonoxy, or halohydrocarbonoxy wherein atleast two carbon atoms separate the halogen and oxygen atoms; and eachQ₂ is independently hydrogen, halogen, primary or secondary alkyl of 1to 7 carbon atoms, phenyl, haloalkyl, hydrocarbonoxy orhalohydrocarbonoxy as defined for Q₁.

[0155] Examples of primary alkyl of 1 to 7 carbon atoms suitable as Q₁and Q₂ are methyl, ethyl, n-propyl, n-butyl, isobutyl, n-amyl, isoamyl,2-methylbutyl, n-hexyl, 2,3-dimethylbutyl, 2-, 3- or 4-methylpentyl andthe corresponding heptyl groups. Examples of secondary alkyl of 1 to 7carbon atoms are isopropyl and sec-butyl.

[0156] Preferably, any alkyl radicals are straight chain rather thanbranched. Most often, each Q₁ is alkyl or phenyl, especially C₁₋₄ alkyl,and each Q₂ is hydrogen. Suitable polyphenylene ethers are disclosed ina large number of patents.

[0157] Both homopolymer and copolymer polyphenylene ethers are included.Suitable homopolymers are those containing, for example2,6-dimethyl-1,4-phenylene ether units. Suitable copolymers includerandom copolymers containing such units in combination with, forexample, 2,3,6-trimethyl-1,4-phenylene ether units. Many suitable randomcopolymers, as well as homopolymers, are disclosed in the patentliterature.

[0158] Also included are polyphenylene ethers containing moieties whichmodify properties such as molecular weight, melt viscosity and/or impactstrength. Such polymers are described in the patent literature and maybe prepared by grafting onto the polyphenylene ether in known mannermonomers such as acrylonitrile or styrene, or polymers such aspolystyrenes or elastomers. The product typically contains both graftedand ungrafted moieties. Other suitable polymers are the coupledpolyphenylene ethers in which the coupling agent is reacted in knownmanner with the hydroxy groups of two polyphenylene ether chains toproduce a higher molecular weight polymer containing the reactionproduct of the hydroxy groups and the coupling agent. Illustrativecoupling agents are low molecular weight polycarbonates quinones,heterocycles and formals.

[0159] The polyphenylene ether generally has a number average molecularweight within the range of about 3,000-40,000 and a weight averagemolecular weight within the range of about 20,000-80,000, as determinedby gel permeation chromatography. Its intrinsic viscosity is most oftenin the range of about 0.15-0.6 dl/g, as measured in chloroform at 25° C.

[0160] The polyphenylene ethers are typically prepared by the oxidativecoupling of at least one corresponding monohydroxyaromatic compound.Particularly useful and readily available monohydroxyaromatic compoundsare 2,6-xylenol, wherein each Q₁ is methyl and each Q₂ is hydrogen andwherein the resultant polymer is characterized as apoly(2,6-dimethyl-1,4-phenylene ether), and 2,3,6-trimethylphenol,wherein each Q₁ and one Q₂ are methyl and the other Q₂ is hydrogen.

[0161] A variety of catalyst systems are known for the preparation ofpolyphenylene ethers by oxidative coupling. There is no particularlimitation as to catalyst choice and any of the known catalysts can beused. For the most part, they contain at least one heavy metal compoundsuch as a copper, manganese or cobalt compound, usually in combinationwith various other materials. A first preferred catalyst systems consistof those containing a copper compound. Such catalysts are disclosed inreferences cited in U.S. Pat. No. 5,100,961. They are usuallycombinations of cuprous or cupric ions, halide (e.g. chloride, bromideor iodide) ions and at least one amine.

[0162] A second preferred class of catalyst systems are those containingmanganese compounds. They are generally alkaline systems in whichdivalent manganese is combined with such anions as halide, alkoxide orphenoxide. Most often the manganese is present as a complex with one ormore complexing and/or chelating agents such as dialkylamines,alkanolamines, alkylenediamines, o-hydroxyaromatic aldehydes,o-hydroxyazo compound, ω-hydroxyoximes (monomeric and polymeric),o-hydroxyaryl oximes and β-diketones. Also useful are knowncobalt-containing catalyst systems. Suitable manganese andcobalt-containing catalyst systems for polyphenylene ether preparationare known in the art by reason of disclosure in numerous patents andpublications.

[0163] The polyphenylene ethers which may be employed for the purposesof this invention include those which comprise molecules having at leastone of the end groups of the formulae

[0164] wherein Q₁ and Q₂ are as previously defined; each R₁₃ isindependently hydrogen or alkyl with the proviso that the total numberof carbon atoms in both R₁₃ radicals is 6 or less; and each R₁₄ isindependently hydrogen or a C₁₋₆ primary alkyl radical. Preferably, eachR₁₃ is hydrogen and each R₁₄ is alkyl, especially methyl or n-butyl.

[0165] Polymers containing the aminoalkyl-substituted end groups offormulae (VI) are typically obtained by incorporating an appropriateprimary or secondary monoamine as one of the constituents of theoxidative coupling reaction mixture, especially when a copper- ormanganese-containing catalyst is used. Such amines, especially thedialkylamines and preferably di-n-butylamine and dimethylamine,frequently become chemically bound to the polyphenylene ether, mostoften by replacing one of the α-hydrogen atoms on one or more Q₁radicals. The principal site of reaction is the Q₁ radical adjacent tothe hydroxy group on the terminal unit of the polymer chain. Duringfurther processing and/or blending, the, aminoalkyl-substituted endgroups may undergo various reactions, probably involving a quinonemethide-type intermediate of the formula

[0166] with numerous beneficial effects often including an increase inimpact strength and compatibilization with other blend components, aspointed out in references cited in U.S. Pat. No. 5,100,961.

[0167] Polymers with 4-hydroxybiphenyl end groups of formula (VII) areoften especially useful in the present invention. They are typicallyobtained from reaction mixtures in which a by-product diphenoquinone ofthe formula

[0168] is present, especially in a copper-halide-secondary or tertiaryamine system, as cited in references in U.S. Pat. No. 5,100,961. Inmixtures of this type, the diphenoquinone is ultimately incorporatedinto the polymer in substantial proportions, largely as an end group.

[0169] In many polyphenylene ethers obtained under the above-describedconditions, a substantial proportion of the polymer molecules, typicallyconstituting as much as about 90% by weight of the polymer, contain endgroups having one or frequently both of formulae (VI) and (VII). Itshould be understood, however, that other end groups may be present andthat the invention in its broadest sense may not be dependent on themolecular structures of the polyphenylene ether end groups.

[0170] The use of polyphenylene ethers containing substantial amounts ofun-neutralized amino nitrogen may afford compositions with undesirablylow impact strengths. The amino compounds include, in addition to theaforementioned aminoalkyl end groups, traces of amine (particularlysecondary amine) in the catalyst used to form the polyphenylene ether.

[0171] The present invention therefore includes the use of polyphenyleneethers in which a substantial proportion of amino compounds has beenremoved or inactivated. Polymers so treated contain un-neutralized aminonitrogen, if any, in amounts no greater than 800 ppm and more preferablyin the range of about 100-800 ppm.

[0172] A preferred method of inactivation is by extrusion of thepolyphenylene ether at a temperature within the range of about 230-350°C., with vacuum venting. This is preferably achieved in a preliminaryextrusion step, by connecting the vent of the extruder to a vacuum pumpcapable of reducing the pressure to about 200 torr or less. There mayalso be advantages in employing vacuum venting during extrusion of thecomposition of this invention.

[0173] It is believed that this inactivation method aids in the removalby evaporation of any traces of free amines (predominantly secondaryamines) in the polymer, including amines generated by conversation ofaminoalkyl end groups to quinone methides as above.

[0174] It will be apparent to those skilled in the art from theforegoing that the polyphenylene ethers contemplated for use in thepresent invention include all those presently known, irrespective ofvariations in structural units or ancillary chemical features.

[0175] The polymer containing amine end groups to be blended with thepolyphenylene ethers or polystyrenes of the present invention ispreferably a polyamide. Included are those prepared by thepolymerization of a monoamino-monocarboxylic acid or a lactam thereofhaving at least 2 carbon atoms between the amino and carboxylic acidgroup, of substantially equimolar proportions of a diamine whichcontains at least 2 carbon atoms between the amino groups and adicarboxylic acid, or of a monoaminocarboxylic acid or a lactam thereofas defined above together with substantially equimolar proportions of adiamine and a dicarboxylic acid. The term “substantially equimolar”proportions includes both strictly equimolar proportions and slightdepartures therefrom which are involved in conventional techniques forstabilizing the viscosity of the resultant polyamides. The dicarboxylicacid may be used in the form of a functional derivative thereof, forexample, an ester or acid chloride.

[0176] Examples of the aforementioned monoamino-monocarboxylic acids orlactams thereof which are useful in preparing the polyamides includethose compounds containing from 2 to 16 carbon atoms between the aminoand carboxylic acid groups, said carbon atoms forming a ring containingthe —CO—NH— group in the case of a lactam. As particular examples ofaminocarboxylic acids and lactams there may be mentioned c-aminocaproicacid, butyrolactam, pivalolactam, ε-caprolactam, capryllactam,enantholactam, undecanolactam, dodecanolactam and 3- and 4-aminobenzoicacids.

[0177] Diamines suitable for use in the preparation of the polyamidesinclude the straight chain and branched chain alkyl, aryl and alkaryldiamines. Illustrative diamines are trimethylenediamine,tetramethylenediamine, pentamethylenediamine, octamethylenediamine,hexamethylenediamine (which is often preferred),trimethylhexamethylenediamine, m-phenylenediamine and m-xylylenediamine.

[0178] The dicarboxylic acids may be represented by the formula

HOOC—B—COOH

[0179] wherein

[0180] B is a divalent aliphatic or aromatic group containing at least 2carbon atoms. Examples of aliphatic acids are sebacic acid,octadecanedioic acid, suberic acid, glutaric acid, pimelic acid andadipic acid.

[0181] Both crystalline and amorphous polyamides may be employed, withthe crystalline species often being preferred by reason of their solventresistance. Typical examples of the polyamides or nylons, as these areoften called, include, for example, polyamide-6 (polycaprolactam), 6,6(polyhexamethylene adipamide), 11, 12, 4,6, 6,10 and 6,12 as well aspolyamides from terephthalic acid and/or isophthalic acid andtrimethylhexamethylenediamine; from adipic acid and m-xylylenediamines;from adipic acid, azelaic acid and 2,2-bis(p-aminophenyl)propane or2,2-bis-(p-aminocyclohexyl)propane and from terephthalic acid and4,4′-diaminodicyclohexylmethane. Mixtures and/or copolymers of two ormore of the foregoing polyamides or prepolymers thereof, respectively,are also within the scope of the present invention. Preferred polyamidesare polyamide-6, 4,6, 6,6, 6,9, 6,10, 6,12, 11 and 12, most preferablypolyamide-6,6.

[0182] Examples of polyesters that form useful blends with polyphenyleneether and polystyrene, which blends may be compatibilized with the(co)oligomers or (co)polymers containing glycidyl and oxyamine groups ofthe instant invention are: Polyethylene terephthalate (PET),polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT),polycyclohexane-1,4-dimethyleneterephthalate (PCT), copolymers of PETand PCT, commonly known as PETG, polyethylene 2,6-naphthalate (PEN) andcopolymers of PET and PEN.

[0183] For the preparation of copolymer compositions according to thisinvention, a blending method which results in the formation of anintimate blend is required. Suitable procedures include solutionblending, although such procedures are of limited applicability to manypolyamides by reason of their insolubility in most common solvents. Forthis reason and because of the availability of melt blending equipmentin commercial polymer processing facilities, melt reaction proceduresare generally preferred. Conventional melt blending procedures andequipment may be employed, with extrusion often preferred because of itsrelative convenience and particular suitability. Typical reactiontemperatures are in the range of about 175°-350° C.

[0184] Those skilled in the art will be familiar with blending methodsand apparatus capable of intimately blending resinous constituents,especially by kneading. They are exemplified by disc-pack processors andvarious types of extrusion equipment. Illustrations of the latter arecontinuous mixers; single screw kneading extruders; counter-rotating,non-intermeshing twin screw extruders having screws which includeforward-flighted compounders, cylindrical bushings and/or left-handedscrew elements; co-rotating, intermeshing twin screw extruders; andextruders having screws which include at least one and preferably atleast two sections of kneading block elements. As previously mentioned,vacuum venting may also be advantageous at this stage.

[0185] It is within the scope of the invention to include in theblending step elastomeric impact modifiers compatible with either orboth of the polymers of components i.) and ii.).

[0186] Impact modifiers for polyphenylene ether-polyamide compositionsare well known in the art. They are typically derived from one or moremonomers selected from the group consisting of olefins, vinyl aromaticmonomers, acrylic and alkylacrylic acids and their ester derivatives aswell as conjugated dienes. Especially preferred impact modifiers are therubbery high-molecular weight materials including natural and syntheticpolymeric materials showing elasticity at room temperature. They includeboth homopolymers and copolymers, including random, block, radial block,graft and core-shell copolymers as well as combinations thereof.

[0187] Polyolefins or olefin-based copolymers employable in theinvention include low density polyethylene, high density polyethylene,linear low density polyethylene, isotactic polypropylene,poly(1-butene), poly(4-methyl-1-pentene), propylene-ethylene copolymersand the like. Additional olefin copolymers include copolymers of one ormore α-olefins, particularly ethylene, with copolymerizable monomersincluding, for example, vinyl acetate, acrylic acids and alkylacrylicacids as well as the ester derivatives thereof including, for example,acrylic acid, ethyl acrylate, methacrylic acid, methyl methacrylate andthe like. Also suitable are the ionomer resins, which may be wholly orpartially neutralized with metal ions.

[0188] A particularly useful class of impact modifiers are those derivedfrom the vinyl aromatic monomers. These include AB and ABA type blockand radial block copolymers and vinyl aromatic conjugated dienecore-shell graft copolymers.

[0189] An especially preferred subclass of vinyl aromaticmonomer-derived resins is the block copolymers comprising monoalkenylarene (usually styrene) blocks and conjugated diene (e.g., butadiene orisoprene) or olefin (e.g., ethylene-propylene, ethylene-butylene) blocksand represented as AB and ABA block copolymers. The conjugated dieneblocks may be partially or entirely hydrogenated, whereupon theproperties are similar to the olefin block copolymers.

[0190] Suitable AB type block copolymers are disclosed in, for example,U.S. Pat. Nos. 3,078,254; 3,402,159; 3,297,793; 3,265,765 and 3,594,452and UK Patent 1,264,741, all incorporated herein by reference. Examplesof typical species of AB block copolymers include:Polystyrene-polybutadiene (SBR), polystyrene-polyisoprene andpoly(α-methylstyrene)-polybutadiene.

[0191] Such AB block copolymers are available commercially from a numberof sources, including Phillips Petroleum under the trademark SOLPRENE.

[0192] Additionally, ABA triblock copolymers and processes for theirproduction as well as hydrogenation, if desired, are disclosed in U.S.Pat. Nos. 3,149,182; 3,231,635; 3,462,162; 3,287,333; 3,595,942;3,694,523 and 3,842,029, all incorporated herein by reference.

[0193] Examples of triblock copolymers include:Polystyrene-polybutadiene-polystyrene (SBS),polystyrene-polyisoprene-polystyrene (SIS),poly(α-methylstyrene)-polybutadiene-poly(α-methylstyrene) andpoly(α-methylstyrene)-polyisoprene-poly(α-methylstyrene).

[0194] Particularly preferred triblock copolymers are availablecommercially as CARIFLEX®, KRATON D®, KRATON G® and KRATON® FG fromShell Chemicals.

[0195] Another class of impact modifiers is derived from conjugateddienes. While many copolymers containing conjugated dienes have beendiscussed above, additional conjugated diene modifier resins include,for example, homopolymers and copolymers of one or more conjugateddienes including, for example, polybutadiene, butadiene-styrenecopolymers, isoprene-isobutylene copolymers, chlorobutadiene polymers,butadiene-acrylonitrile copolymers, polyisoprene, and the like.Ethylene-propylene-diene monomer rubbers may also be used. These EPDM'sare typified as comprising predominantly ethylene units, a moderateamount of propylene units and up to about 20 mole percent ofnon-conjugated diene monomer units. Many such EPDM's and processes forthe production thereof are disclosed in U.S. Pat. Nos. 2,933,480;3,000,866; 3,407,158; 3,093,621 and 3,379,701, incorporated herein byreference.

[0196] Other suitable impact modifiers are the core-shell type graftcopolymers. In general, these have a predominantly conjugated dienerubbery core or a predominantly cross-linked acrylate rubbery core andone or more shells polymerized thereon and derived from monoalkenylareneand/or acrylic monomers alone or, preferably, in combination with othervinyl monomers. Such core-shell copolymers are widely availablecommercially, for example, from Rohm and Haas Company under the tradenames KM-611, KM-653 and KM-330, and are described in U.S. Pat Nos.3,808,180; 4,034,013; 4,096,202; 4,180,494 and 4,292,233.

[0197] Also useful are the core-shell copolymers wherein aninterpenetrating network of the resins employed characterizes theinterface between the core and shell. Especially preferred in thisregard are the ASA type copolymers available from General ElectricCompany and sold as GELOY™ resin and described in U.S. Pat. No.3,944,631.

[0198] In addition, there may be employed the above-described polymersand copolymers having copolymerized therewith or grafted thereonmonomers having functional groups and/or polar or active groups.Finally, other suitable impact modifiers include Thiokol rubber,polysulfide rubber, polyurethane rubber, polyether rubber (e.g.,polypropylene oxide), epichlorohydrin rubber, ethylene-propylene rubber,thermoplastic polyester elastomers and thermoplastic ether-ester andether-amide elastomers.

[0199] The proportion of impact modifier or other resinous material issubject to wide variation. Impact modifiers such as diblock or triblockcopolymers are usually present in an amount up to about 50 parts per 100parts of the polymer of component i).

[0200] Provided the necessity for intimate blending is strictlyobserved, the order of blending may be varied. It is often foundadvantageous to employ an extruder which has at least two ports forintroduction of ingredients, one such port being downstream from theother. The polymer of component i.) and at least a portion of the impactmodifier are introduced through the first port and extruded. Thisportion of the extruder is often preferably vacuum vented.

[0201] The polyamide or polyester and any additional impact modifier areintroduced through the downstream port and extrusion is continued,preferably at a lower temperature to minimize degradation of the impactmodifier. By this method, optimum dispersion may be achieved, witheither polymer being the continuous phase depending on proportion andmethod of blending.

[0202] The polymer blends of the instant invention may be furtherenhanced by the addition of polyamide stabilizers, for example coppersalts in combination with iodides and/or phosphorus compounds and saltsof divalent manganese, flow modifiers, fillers, flame retardants,pigments, dyes, stabilizers, anti-static agents, crystallization aids,mold release agents and the like, as well as resinous components notpreviously discussed.

[0203] The principal reaction which takes place between theglycidyl-nitroxide end-capped (co)oligomers and (co)polymers of theinstant invention and the polyamide generally involves the amine endgroups of the latter, which are nucleophilic and open the epoxide ringto form amino alcohol groups. Another possible reaction is betweencarboxylic acid end groups of the polyamide and the epoxy groups of the(co)oligomers and (co)polymers. In the case of polyesters, thecarboxylic acid end groups are reactive towards glycidyl groups.

[0204] The amount of the glycidyl-nitroxide end-capped (co)oligomers or(co)polymers employed is generally in the range of about 5% to about 30%by weight, based on the overall formulation.

[0205] The proportions of the polymer of component i.) and the otherpolymer employed for the preparation of the compositions of thisinvention are not critical; they may be widely varied to providecompositions having the desired properties. Most often, the weight ratioof the two polymers are from about 1:10 to about 10:1. Preferably, theweight ratio of the polymer of component i.) and the other polymer isfrom about 3:7 to about 7:3.

[0206] In addition to epoxy-polymer-polyamide copolymer, orepoxy-polymer-polyester copolymer, the compositions of this inventionalso contain unreacted polyamide or polyester. In any event, moldedparts produced from said compositions are generally ductile and havehigher impact strengths than those produced from simple polymer blends,which are incompatible and often have poor mechanical properties aspreviously described.

[0207] The following Examples illustrate the invention in more detail.They are not to be construed as limiting the instant invention in anymanner whatsoever. The invention is declared to cover all changes andmodifications of the specific examples which do not constitute departurefrom the spirit and scope of the invention.

EXAMPLE 1 Preparation of1-(4-glycidyloxyphenyl)-1-(2,2,6,6-tetramethyl-4-n-propoxypiperidin-1-oxy)ethane

[0208] A): A 70% aqueous solution of t-butylhydroperoxide (26.4 g) isextractively dehydrated in two portions with each of 25 g glycidyl4-ethylphenyl ether. The organic extracts are combined, a molecularsieve is added and the mixture is stored under argon atmosphere.

[0209] B): A mixture of glycidyl 4-ethylphenyl ether (57 g),4-propoxy-2,2,6,6-tetramethylpiperidine-1-oxyl (10.7 g) andmolybdenum(VI)oxide (0.72 g) are purged with argon for one hour. Themixture is then heated up to 70° C. and the solution prepared under A)is added under stirring within 30 minutes. Pressure is reduced to 200mbar and the mixture is heated for 18 hours at 100° C. After thereaction is completed the mixture is cooled to room temperature and thepressure is allowed to raise to normal pressure. Ethyl acetate and waterare added. The water phase is separated and extracted once with ethylacetate. The organic phases are combined, washed with a 10% solution ofsodium ascorbate and in a second step with water, dried over sodiumsulfate and concentrated. Excessive amounts of glycidyl 4-ethylphenylether are removed at 80° C./0.01 mbar. The raw product is purified bychromatography on silica with a 7:1 mixture of petrolether/ethyl acetateas the eluent. A clear colorless oil is obtained, corresponding to thecompound of formula (101).

[0210] Elemental Analysis: calculated for C₂₃H₃₇NO₄: 70.55% C; 9.52% H;3.57% N found: 70.66% C; 9.60% H.; 3.43% N

EXAMPLE 2 Polymerization of Styrene

[0211] In a Schlenk tube the amount of1-(4-glycidyloxyphenyl)-1-(2,2,6,6-tetramethyl-4-n-propoxypiperidin-1-oxy)ethane(compound 101) in Table 1 is dissolved in 50 mL of distilled styrene.The solution is degassed according to the freeze and thaw technique andflushed with argon. After heating for 6 hours in an oil bath to thetemperature given in table 1 the excess monomer is removed under vacuumand the resulting white polymer is dried in a drying oven under vacuum.Weight average ({overscore (M)}w) and number average ({overscore (M)}n)molecular weights are determined using gel permeation chromatography(GPC). Results are given in Table 1. TABLE 1 Compound Temp. 101Conversion Run (° C.) (g, mmol) (percent) {overscore (M)}w {overscore(M)}n {overscore (M)}w/{overscore (M)}n 1 120 0.170, 0.435 36 4550032800 1.39 2 120 0.392, 1.00  16 13480  8620 1.56 3 130 0.170, 0.435 5259400 44100 1.32

EXAMPLE 3 Impact Strength and Tensile Properties of PPE/PA-6,6 Blends

[0212] The tested are described in Table 2 below. All amounts arepercent by weight of the overall formulation. TABLE 2 Formulation No.PPE PA-6,6 Impact Modifier PS 1 50 50 — — 2 45 45 10 — 3 45 45 10 — 4 4040 10 10 5 37.5 37.5 10 15

[0213] The polyphenylene ether (PPE) is apoly(2,6-dimethyl-1,4-phenylene ether), BLENDEX® HPP820, available fromGE Specialty Chemicals, with a specific gravity of 1.06 g/cm³ and anintrinsic viscosity in chloroform at 25° C. of 0.4 dl/g.

[0214] The polyamide (PA-6,6) is a commercially available polyamide-6,6,ZYTEL® 101L, available from DuPont.

[0215] The impact modifier is KRATON® FG, available from ShellChemicals, a maleic anhydride functionalized triblock copolymer withpolystyrene end-blocks and poly(ethylene/butylene) mid-blocks.

[0216] The polystyrene (PS) is a polystyrene of the present inventionprepared as above and has a {overscore (M)}w of 4500.

[0217] Mixtures of the formulations of Table 2 are dry-blended andextruded with a 27 mm Leistritz twin screw extruder at 235, 265, 270 and275° C. The extruded pellets are injection molded in a BOY 50M injectionmolder at 255, 265 and 275° C. with a nozzle temperature of 275° C. anda mold temperature of 150° C.

[0218] The formulations of Table 2 are tested for Notched Izod impactstrength according to ASTM method D256. Results are given in Table 3below. The formulations of Table 2 are also tested for tensileproperties according to ASTM method D638. TABLE 3 Tensile Notched IzodStrength Total Formulation Impact Strength at Break Elongation Energy toNo. (ft. lb./in) (kg/mm²) (percent) Break (kg-mm) 1 0.54 6.2 15 27 20.45 4.7 18 28 3 0.47 4.5 17 26 4 1.13 5.4 18 36 5 1.67 5.0 27 57

[0219] It is seen that the polyphenylene ether-polyamide mixturesblended with a polymer containing glycidyl and oxyamine groups of theinstant invention exhibits outstanding mechanical properties asexhibited by impact strength and tensile properties.

EXAMPLE 4 Impact Strength and Tensile Properties of PPE/PA-6,6 Blends

[0220] The formulations tested are described in Table 4 below. Allamounts are percent by weight of the overall formulation. TABLE 4 Formu-Impact PS PS PS PS lation No. PPE PA-6,6 Modifier MC3700 Rad.Poly. A B 650 50 — — — — — 7 45 45 10 — — — — 8 37.5 37.5 10 15 — — — 9 37.5 37.510 — 15 — — 10 40 40 10 — — 10 — 11 37.5 37.5 10 — — 15 — 12 40 40 10 —— — 10 13 37.5 37.5 10 — — — 15

[0221] The polyphenylene ether (PPE) is apoly(2,6-dimethyl-1,4-phenylene ether), BLENDEX® HPP820, available fromGE Specialty Chemicals, with a specific gravity of 1.06 g/cm³ and anintrinsic viscosity in chloroform at 25° C. of 0.4 dl/g.

[0222] The polyamide (PA-6,6) is a commercially available polyamide-6,6,ZYTEL® 101L, available from DuPont.

[0223] The impact modifier is KRATON® FG, available from ShellChemicals, a maleic anhydride functionalized triblock copolymer withpolystyrene end-blocks and poly(ethylene/butylene) mid-blocks.

[0224] The polystyrene PS MC3700 is a polystyrene of broad molecularweight distribution prepared by conventional radical polymerization,available from Chevron and has a {overscore (M)}w of 205,000, a{overscore (M)}n of 80,000 and a {overscore (M)}w/{overscore (M)}n of2.56.

[0225] The polystyrene PS Rad.Polym. is a polystyrene of broad molecularweight distribution prepared by conventional radical polymerization andhas a {overscore (M)}w of 25,900, a {overscore (M)}n of 13,300 and a{overscore (M)}w/{overscore (M)}n of 1.95.

[0226] The polystyrene PS A is a polystyrene of the present inventionand is prepared as above and has a {overscore (M)}w of 41,400, a{overscore (M)}n of 30,500 and a {overscore (M)}w/{overscore (M)}n of1.36.

[0227] The polystyrene PS B is a polystyrene of the present inventionand is prepared as above and has a {overscore (M)}w of 8,800, a{overscore (M)}n of 7,200 and a {overscore (M)}w/{overscore (M)}n of1.22.

[0228] Mixtures of the formulations of Table 4 are dry-blended andextruded with a 27 mm Leistritz twin screw extruder at 235, 265, 270 and275° C. The extruded pellets are injection molded in a BOY 50M injectionmolder at 255, 265 and 275° C. with a nozzle temperature of 275° C. anda mold temperature of 150° C.

[0229] The formulations of Table 4 are tested for Notched Izod impactstrength according to ASTM method D256. Results are given in Table 5below. The formulations of Table 4 are also tested for tensileproperties according to ASTM method D638. TABLE 5 Tensile Notched IzodStrength Total Formulation Impact Strength at Break Elongation Energy toNo. (ft. lb./in) (kg/mm²) (percent) Break (kg-mm) 6 0.7 6.8 14 22 7 0.454.8 17 24 8 0.8 5.6 16 26 9 0.9 5.6 16 25 10 0.9 5.6 24 44 11 1.4 6.0 3167 12 1.2 5.5 23 43 13 1.6 6.1 82 205 

[0230] It is seen that the polyphenylene ether-polyamide mixturesblended with a polymer containing glycidyl and oxyamine groups of theinstant invention exhibits outstanding mechanical properties asexhibited by impact strength and tensile properties.

EXAMPLE 5 Impact Strength and Tensile Properties of PPE/PA-6 Blends

[0231] The experiments of Example 4 are repeated using polyamide-6instead of polyamide6,6. The polyphenylene ether-polyamide mixturesblended with a polymer containing glycidyl and oxyamine groups of theinstant invention exhibits outstanding mechanical properties asexhibited, by impact strength and tensile properties.

EXAMPLE 6 Impact Strength and Tensile Properties of PPE/Polyester Blends

[0232] The experiments of Example 4 are repeated using polyethyleneterephthalate (PET), polybutylene terephthalate (PBT), polytrimethyleneterephthalate (PTT), polycyclohexane-1,4-dimethyleneterephthalate (PCT),copolymers of PET and PCT, commonly known as PETG, polyethylene2,6-naphthalate (PEN) and copolymers of PET and PEN instead ofpolyamide-6,6. The polyphenylene ether-polyester mixtures blended with apolymer containing glycidyl and oxyamine groups of the instant inventionexhibit outstanding mechanical properties as exhibited by impactstrength and tensile properties.

EXAMPLE 7 Impact Strength and Tensile Properties ofPolystyrene/Polyamide Blends

[0233] The experiments of Example 4 are repeated using polystyreneinstead of polyphenylene ether. The polystyrene-polyamide mixturesblended with a polymer containing glycidyl and oxyamine groups of theinstant invention exhibits outstanding mechanical properties asexhibited by impact strength and tensile properties.

EXAMPLE 8 Impact Strength and Tensile Properties ofPolystyrene/Polyester Blends

[0234] The experiments of Example 6 are repeated using polystyreneinstead of polyphenylene ether. The polystyrene-polyester mixturesblended with a polymer containing glycidyl and oxyamine groups of theinstant invention exhibits 6outstanding mechanical properties asexhibited by impact strength and tensile properties.

What is claimed is:
 1. A composition comprising i.) a polymer selectedfrom the group consisting of polyphenylene ether and polystyrene, ii.)at least one other polymer containing amine or carboxylic acid endgroups, and iii.) an oligomer, polymer, cooligomer or copolymer preparedby free-radical polymerization of at least one ethylenically unsaturatedmonomer or oligomer in the presence of a glycidyl-functionalizednitroxyl initiator.
 2. A composition according to claim 1 in which thepolyphenylene ether comprises a plurality of structural units having theformula

wherein in each of said units independently, each Q₁ is independentlyhalogen, primary or secondary alkyl of 1 to 7 carbon atoms, phenyl,haloalkyl, aminoalkyl, hydrocarbonoxy, or halohydrocarbonoxy wherein atleast two carbon atoms separate the halogen and oxygen atoms; and eachQ₂ is independently hydrogen, halogen, primary or secondary alkyl of 1to 7 carbon atoms, phenyl, haloalkyl, hydrocarbonoxy orhalohydrocarbonoxy as defined for Q₁.
 3. A composition according toclaim 2 in which the polyphenylene ether is apoly(2,6-dimethyl-1,4-phenylene ether).
 4. A composition according toclaim 1 in which component ii.) is selected from the group consisting ofpolyamide and polyester.
 5. A composition according to claim 4 in whichthe polyamide is a polyamide-6 or polyamide-6,6.
 6. A compositionaccording to claim 4 in which the polyester is selected from the groupconsisting of polyethylene terephthalate, polybutylene terephthalate,polytrimethylene terephthalate,polycyclohexane-1,4-dimethyleneterephthalate, polyethyleneterephthalate/polycyclohexane-1,4-dimethyleneterephthalate copolymer,polyethylene 2,6-naphthalate and polyethylene terephthalate/polyethylene2,6-naphthalate copolymer.
 7. A composition according to claim 1 whereinthe glycidyl-functionalized nitroxyl initiator is of the formula

wherein R are independently hydrogen, halogen, NO₂, cyano, —CONR₅R₆,—(R₉)COOR₄, —C(O)R₇, —OR₈, —SR₈, —NHR₈, —N(R₈)₂, carbamoyl,di(C₁-C₁₈alkyl)carbamoyl, —C(═NR₅)(NH₆) or R has the same definition asR₁; R₁ are independently unsubstituted C₁-C₁₈alkyl, C₂-C₁₈alkenyl,C₂-C₁₈alkynyl, C₇-C₉phenylalkyl, C₃-C₁₂cycloalkyl orC₂-C₁₂heterocycloalkyl; or C₁-C₁₈alkyl, C₂-C₁₈alkenyl, C₂-C₁₈alkynyl,C₇-C₉phenylalkyl, C₃-C₁₂cycloalkyl or C₂-C₁₂heterocycloalkyl, which aresubstituted by NO₂, halogen, amino, hydroxy, cyano, carboxy,C₁-C₄alkoxy, C₁-C₄alkylthio, C₁-C₄alkylamino or di(C₁-C₄alkyl)amino; orphenyl, naphthyl, which are unsubstituted or substituted by C₁-C₄alkyl,C₁-C₄alkoxy, C₁-C₄alkylthio, halogen, cyano, hydroxy, carboxy,C₁-C₄alkylamino or di(C₁-C₄alkyl)amino; R₄ is hydrogen, C₁-C₁₈alkyl,phenyl, an alkali metal cation or a tetraalkylammonium cation; R₅ and R₆are hydrogen, C₁-C₁₈alkyl, C₂-C₁₈alkyl which is substituted by at leastone hydroxy group or, taken together, form a C₂-C₁₂alkylene bridge or aC₂-C₁₂-alkylene bridge interrupted by at least one O or/and NR₈ atom; R₇is hydrogen, C₁-C₁₈alkyl or phenyl; R₈ is hydrogen, C₁-C₁₈alkyl orC₂-C₁₈alkyl which is substituted by at least one hydroxy group; R₉ isC₁-C₁₂alkylene or a direct bond; or all R₁ form together the residue ofa polycyclic cycloaliphatic ring system or a polycyclicheterocycloaliphatic ring system with at least one di- or trivalentnitrogen atom; R₂ are independently of each other phenyl or C₁-C₆alkylor two together with the linking carbon atom form a C₅-C₆cycloalkylgroup; A is a divalent group which forms a carbocyclic or heterocyclic5-, 6- or 7-membered ring which may be further substituted; and R₃ is aradical of formula (I)

X is phenylene, naphthylene or biphenylene, which are unsubstituted orsubstituted by NO₂, halogen, amino, hydroxy, cyano, carboxy,C₁-C₄alkoxy, C₁-C₄alkylthio, C₁-C₄alkylamino or di(C₁-C₄alkyl)amino; R₁₂are independently of each other H or CH₃; D is a group

and m is a number from 1 to
 4. 8. A composition according to claim 7wherein the glycidyl-functionalized nitroxyl initiator is of the formula(Ib) wherein R₂ are independently CH₃ or C₂H₅; A is —CH₂OC(O)—, —OCH₂—,C₂-C₃alkylene, C₂-C₃alkenylene, or 1,2-phenylene, or said C₂-C₃alkylene,C₂-C₃alkenylene and 1,2-phenylene groups substituted by hydroxy,C₁-C₁₈alkylcarboxy, C₁-C₁₈alkoxy, benzyloxy, C₁-C₁₈alkanoyloxy,benzoyloxy, C₁-C₁₈alkylamino or di(C₁-C₁₈alkyl)amino; and R₃ is aradical of formula (II)

X is phenylene, naphthylene or biphenylene; one R₁₂ is H and the otherR₁₂ is CH₃; D is a group

and m is a number from 1 to
 2. 9. A composition according to claim 8wherein the glycidyl-functionalized nitroxyl initiator is of the formula

Y is H, OR₁₀, NR₁₀R₁₁ or —O—C(O)—R₁₀; and R₁₀ and R₁₁ independently arehydrogen or C₁-C₁₈alkyl.
 10. A composition according to claim 9 whereinthe glycidyl-functionalized nitroxyl initiator is of the formula (III)wherein

Y is H, OR₁₀, NR₁₀R₁₁ or —O—C(O)—R₁₀; and R₁₀ and R₁₁ are independentlyhydrogen or C₁-C₆alkyl.
 11. A composition according to claim 10 whereinthe glycidyl-functionalized nitroxyl initiator is of the formula


12. A composition according to claim 1 in which the ethylenicallyunsaturated monomer is selected from the group consisting of styrene,α-methylstyrene, p-methylstyrene, isoprene and butadiene.
 13. Acomposition according to claim 1 in which the ethylenically unsaturatedmonomer is styrene.
 14. A composition according to claim 7 in which theoligomer, polymer, cooligomer or copolymer prepared by free-radicalpolymerization of at least one ethylenically unsaturated monomer oroligomer in the presence of a glycidyl-functionalized nitroxyl initiatorcontains at least one initiator group —R₃ and at least one oxyaminegroup of formula


15. A composition according to claim 1 which further comprises anelastomeric impact modifier.
 16. A composition according to claim 15 inwhich the impact modifier is a triblock copolymer wherein the end-blocksare polystyrene and the mid-block is selected from the group consistingof polyisoprene, polybutadiene, poly(ethylene/butylene) andpoly(ethylene/propylene).
 17. A composition according to claim 16 inwhich the mid-block has been hydrogenated.
 18. A composition accordingto claim 16 in which the triblock copolymer is functionalized withmaleic anhydride.
 19. A method for preparing highly compatiblepolyphenylene ether-polyamide mixtures which comprises blending underintimate blending conditions i.) a polymer selected from the groupconsisting of polyphenylene ether and polystyrene, ii.) at least oneother polymer containing amine or carboxylic acid end groups, iii.) anoligomer, polymer, cooligomer or copolymer prepared by free-radicalpolymerization of at least one ethylenically unsaturated monomer oroligomer in the presence of a glycidyl-functionalized nitroxylinitiator, and iv.) optional further additives.
 20. A method accordingto claim 19 in which the polyphenylene ether comprises a plurality ofstructural units having the formula

wherein in each of said units independently, each Q₁ is independentlyhalogen, primary or secondary alkyl of 1 to 7 carbon atoms, phenyl,haloalkyl, aminoalkyl, hydrocarbonoxy, or halohydrocarbonoxy wherein atleast two carbon atoms separate the halogen and oxygen atoms; and eachQ₂ is independently hydrogen, halogen, primary or secondary alkyl of 1to 7 carbon atoms, phenyl, haloalkyl, hydrocarbonoxy orhalohydrocarbonoxy as defined for Q₁.
 21. A method according to claim 20in which the polyphenylene ether is a poly(2,6-dimethyl-1,4-phenyleneether).
 22. A method according to claim 19 in which component ii.) isselected from the group consisting of polyamide and polyester.
 23. Amethod according to claim 22 in which the polyamide is a polyamide-6 orpolyamide-6,6.
 24. A method according to claim 22 in which the polyesteris selected from the group consisting of polyethylene terephthalate,polybutylene terephthalate, polytrimethylene terephthalate,polycyclohexane-1,4-dimethyleneterephthalate, polyethyleneterephthalate/polycyclohexane-1,4-dimethyleneterephthalate copolymer,polyethylene 2,6-naphthalate and polyethylene terephthalate/polyethylene2,6-naphthalate copolymer.
 25. A method according to claim 19 whereinthe glycidyl-functionalized nitroxyl initiator is of the formula

wherein R are independently hydrogen, halogen, NO₂, cyano, —CONR₅R₆,—(R₉)COOR₄, —C(O)—R₇, —OR₈, —SR₈, —NHR₈, —N(R₈)₂, carbamoyl,di(C₁-C₁₈alkyl)carbamoyl, —C(═NR₅)(NHR₆) or R has the same definition asR₁; R₁ are independently unsubstituted C₁-C₁₈alkyl, C₂-C₁₈alkenyl,C₂-C₁₈alkynyl, C₇-C₉phenylalkyl, C₃-C₁₂cycloalkyl orC₂-C₁₂heterocycloalkyl; or C₁-C₁₈alkyl, C₂-C₁₈alkenyl, C₂-C₁₈ alkynyl,C₇-C₉phenylalkyl, C₃-C₁₂cycloalkyl or C₂-C₁₂heterocycloalkyl, which aresubstituted by NO₂, halogen, amino, hydroxy, cyano, carboxy,C₁-C₄alkoxy, C₁-C₄alkylthio, C₁-C₄alkylamino or di(C₁-C₄alkyl)amino; orphenyl, naphthyl, which are unsubstituted or substituted by C₁-C₄alkyl,C₁-C₄alkoxy, C₁-C₄alkylthio, halogen, cyano, hydroxy, carboxy,C₁-C₄alkylamino or di(C₁-C₄alkyl)amino; R₄ is hydrogen, C₁-C₁₈alkyl,phenyl, an alkali metal cation or a tetraalkylammonium cation; R₅ and R₆are hydrogen, C₁-C₁₈alkyl, C₂-C₁₈alkyl which is substituted by at leastone hydroxy group or, taken together, form a C₂-C₁₂alkylene bridge or aC₂-C₁₂-alkylene bridge interrupted by at least one O or/and NR₈ atom; R₇is hydrogen, C₁-C₁₈alkyl or phenyl; R₈ is hydrogen, C₁-C₁₈alkyl orC₂-C₁₈alkyl which is substituted by at least one hydroxy group; R₉ isC₁-C₁₂alkylene or a direct bond; or all R₁ form together the residue ofa polycyclic cycloaliphatic ring system or a polycyclicheterocycloaliphatic ring system with at least one di- or trivalentnitrogen atom; R₂ are independently of each other phenyl or C₁-C₆alkylor two together with the linking carbon atom form a C₅-C₆cycloalkylgroup; A is a divalent group which forms a carbocyclic or heterocyclic5-, 6- or 7-membered ring which may be further substituted; and R₃ is aradical of formula (II)

X is phenylene, naphthylene or biphenylene, which are unsubstituted orsubstituted by NO₂, halogen, amino, hydroxy, cyano, carboxy,C₁-C₄alkoxy, C₁-C₄alkylthio, C₁-C₄alkylamino or di(C₁-C₄alkyl)amino; R₁₂are independently of each other H or CH₃; D is a group

m is a number from 1 to
 4. 26. A method according to claim 25 whereinthe glycidyl-functionalized nitroxyl initiator is of the formula (Ib)wherein R₂ are independently CH₃ or C₂H₅; A is —CH₂OC(O)—, —OCH₂—,C₂-C₃alkylene, C₂-C₃alkenylene, or 1,2-phenylene, or said C₂-C₃alkylene,C₂-C₃alkenylene and 1,2-phenylene groups substituted by hydroxy,C₁-C₁₈alkylcarboxy, C₁-C₁₈alkoxy, benzyloxy, C₁-C₁₈alkanoyloxy,benzoyloxy, C₁-C₁₈alkylamino or di(C₁-C₁₈alkyl)amino; and R₃ is aradical of formula (II)

X is phenylene, naphthylene or biphenylene; one R₁₂ is H and the otherR₁₂ is CH₃; D is a group

m is a number from 1 to
 2. 27. A method according to claim 26 whereinthe glycidyl-functionalized nitroxyl initiator is of the formula

Y is H, OR₁₀, NR₁₀R₁₁ or —O—C(O)—R₁₀; and R₁₀ and R₁₁ independently arehydrogen or C₁-C₁₈alkyl.
 28. A method according to claim 27 wherein theglycidyl-functionalized nitroxyl initiator is of the formula (III)wherein

Y is H, OR₁₀, NR₁₀R₁₁ or —O—C(O)—R₁₀; and R₁₀ and R₁₁ are independentlyhydrogen or C₁-C₆alkyl.
 29. A method according to claim 28 wherein theglycidyl-functionalized nitroxyl initiator is of the formula


30. A method according to claim 19 in which the ethylenicallyunsaturated monomer is selected from the group consisting of styrene,α-methylstyrene, p-methylstyrene, isoprene and butadiene.
 31. A methodaccording to claim 19 in which the ethylenically unsaturated monomer isstyrene.
 32. A method according to claim 25 in which the oligomer,polymer, cooligomer or copolymer prepared by free-radical polymerizationof at least one ethylenically unsaturated monomer or oligomer in thepresence of a glycidyl-functionalized nitroxyl initiator contains atleast one initiator group —R₃ and at least one oxyamine group of formula


33. A method according to claim 18 which component iv.) is anelastomeric impact modifier.
 34. A composition according to claim 33 inwhich the impact modifier is a triblock copolymer wherein the end-blocksare polystyrene and the mid-block is selected from the group consistingof polyisoprene, polybutadiene, poly(ethylene/butylene) andpoly(ethylene/propylene).
 35. A method according to claim 34 in whichthe mid-block has been hydrogenated.
 36. A composition according toclaim 34 in which the triblock copolymer is functionalized with maleicanhydride.